Why did the USA lose the Vietnam War?

The Americans did not lose purely for military reasons. There were other factors as well.

Write an explanation AND cite a source which shows the importance of the following six factors:

1. US military tactics in Vietnam
Conventional methods. Well maybe not entirely conventional but the US army went into Viet Nam with the intention of fighting battles in a somewhat organized fashion. However as time went on US generals soon learned that this was not a possibility due to the Viet Cong's method of Guerilla warfare.
Source 37
2. The unpopularity of the South Vietnamese regime
During eisenhower's years as president the US government had showed support for the ruler of south Viet Nam, Diem. Diem may have supported democracy but he was a corrupt ruler and was not popular with the people of south Viet Nam, particularly buddhists.
Source 33
3. The experience of the Viet Cong and the inexperience of the American soldiers
many of the american soldiers had been drafted and were at a young age whereas the Viet Cong soldiers were used to fighting in the jungle and using geurila warfare. They were also fighting for their independence or that how they felt so they were much more motivated.
Source 53
4. Domestic opposition to the war in the U.S.
The war was greatly opposed within the US especially by colege students who either didn't believe in the principle of the war or they did not wish to be drafted.
Souurce 42 images like this were broadcast on american television and caused many americans to question the US's tactics in fighting the war
5. Chinese and Soviet support for the Viet Cong
Both China and the Soviet Union supported the Viet Cong the USSR sent many suplies to China which were then transported via the Ho Chi Minh trail into North and then south Viet Nam.
Source 31
6. 'But did they really lose?' Summarize the argument put forward in Source 57, and your view on it.
Nixon would like us to believe that we achieved peace with honor but unfortunately while we may have atained peace at the end of the war we did not have honor for what we had done in Viet Nam. We had not fought bravely but from a distance. Niether side had won. For while the US left Viet Nam the Viet Cong had distroyed their country and it would take decades to rebuild all that they had lost. America had not achieved its goal in containing communism.
Add other if you think there are factors you should consider.